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LipschutzDavid-7193 asked joyceshen-MSFT commented

On Premise Exchange Server after wonky migration to Identity Hybrid

We were hit with a ransomware attack back in 2019 and lost our Exchange Server 2016. We synced our users from Active Directory to 365 and gave them new mailboxes. Then, we reinstalled Exchange 2016 and restored our old mailboxes. We migrated users' messages from their old mailboxes on the restored-on-premise-server to their new 365 mailboxes. What does this give us? “Identity Hybrid”? The on-premise Exchange server is 2016 with CU19 installed on Windows 2016. It still has all the server roles and footprint as when it was a mailbox and transport server. I’m not confident in my AD setup as far as Exchange is concerned. I’d like to get that disk space back and clean up my environmCan ent. Can I remove the old unused mailboxes and the any link from the AD accounts to them? Can I remove the unused server roles from the server and from Active Directory. Can I migrate the 2016 server to a new server Exchange 2019 on Windows 2019 with only with only the hardware and functionality needed for “Identity Hybrid”? Or decomission the server and install a 2019 server on-premise for management?

Sorry if I got the tags wrong, or composed the descripton of this mess poorly

office-exchange-server-administrationoffice-exchange-online-itpro
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joyceshen-MSFT answered joyceshen-MSFT commented

Hi @LipschutzDavid-7193

The official document here introduced about the What is hybrid identity with Azure Active Directory?

What migration method did you use to finish this? "We migrated users' messages from their old mailboxes on the restored-on-premise-server to their new 365 mailboxes."

Did you run the HCW to deploy a hybrid between your on-premise Exchange server and O365?

And now the mailboxes are located in cloud and they still use AAD connect to sync from on-premise right? Correct me if I have any misunderstanding about your environment.

If you run HCW before to deploy a hybrid, and you have all of mailboxes in Exchange Online. Do not need to manage my users from on-premises and no longer have a need for directory synchronization or password synchronization. Refer to the Scenario one in this official document.

If you didn't deploy a hybrid previously, refer to this link: Convert Synced user to In Cloud Only User Account on Office365

Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.


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Other issues pulled me away. Please bear with me. I value your response and want to address it.

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Hi,

Waiting for your feedback here.

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LipschutzDavid-7193 avatar image
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LipschutzDavid-7193 answered joyceshen-MSFT commented

I really can't remember how we migrated the messages.
I think some sort of export / import.
Can remember how we got Hybrid set up either.
I don't think it was the wizard.
There is a mailbox in the cloud currently used, and an unused mailbox containing the migrated messages on-premise, for each user.
I will follow your provided links asap.
I thought I had some time carved out when I posted this.

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Hi

If the account in o365 is not synced from your on-prem server, you just created them manually and use export/import pst to migrate the mailbox data, the on-prem accounts and the cloud accounts should not be associated.

If your 365 accounts have properties synced from on-prem, you will need to use the solution in the above link to make them cloud only. Then you can safely remove them from on-prem server.

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LipschutzDavid-7193 avatar image
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LipschutzDavid-7193 answered

I am Scenario two.
I am digesting the article
My public folders are migrated but the on premise server still says.
PublicFoldersEnabled : Local

I'll keep reading




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LipschutzDavid-7193 answered joyceshen-MSFT commented

https://docs.microsoft.com/en-us/exchange/troubleshoot/user-and-shared-mailboxes/mailbox-exists-exo-onpremises
From this article, I am able to
Disable-Mailbox "mailbox identity"
then
Enable-RemoteMailbox "user identity" -RemoteRoutingAddress "user@contoso.mail.onmicrosoft.com"
That leaves me seeing the user as "Mailbox Type" "Office 365" on my on premise server ecp.
I think that is what I need to do, right?
But now I will need to do that for ALL my users.

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Hi

The official document applies to your users have a mailbox in both Exchange Online and an Exchange on-premises organization.

If you are in this scenario, just follow the steps to keep the mailbox in only one side. Then you will still need to move the users to another unsynced OU to stop from syncing.

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The mailbox on premise is the old mailbox we exported their messages from.
I do want the accounts to sync.

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Hi

Check if your scenario meet the situation described in the link, you could check this below link as well:

Fix mailbox showing up in both Exchange Online and on-premises | Exchange Hybrid

Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.


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LipschutzDavid-7193 avatar image
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LipschutzDavid-7193 answered joyceshen-MSFT commented

All mail flow is as expected.
No issues there.
I think this would work for me other than any aliases.
I would also need my account creation to handle the enable-remotemailbox.

Disable-Mailbox "mailbox identity"
then
Enable-RemoteMailbox "user identity" -RemoteRoutingAddress "user@contoso.mail.onmicrosoft.com"
That leaves me seeing the user as "Mailbox Type" "Office 365" on my on premise server ecp.
I think that is what I need to do, right?
But now I will need to do that for ALL my users.

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Hi,

If you want to perform the operation for all your users:

Powershell to enable remote mailbox from bulk users from a csv


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